We obtained highly n-type doped graphene by intercalating terbium atoms between graphene and SiC(0001) through appropriate annealing in UHV. After terbium intercalation angle-resolvedphotoelectron spectroscopy (ARPES) showed a drastic change in the band structure around the K-points of the Brillouin zone: the well-known conical dispersion band of a graphene monolayer was superposed by a second conical dispersion band of a graphene monolayer with an electron density reaching 10 15 cm −2 . In addition, we demonstrate that atom intercalation proceeds either below the buffer layer or between the buffer layer and monolayer graphene. The intercalation of terbium below a pure buffer layer led to the formation of a highly n-doped graphene monolayer decoupled from the SiC substrate, as evidenced by ARPES and XPS measurements. The band structure of this highly n-doped monolayer graphene showed a kink (a deviation from the linear dispersion of the Dirac-cone) which has been associated to electron-phonon coupling constant one order of magnitude larger than those usually obtained for graphene with intercalated alkali metals.

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We report on the first all-epitaxial ferromagnet/inorganic semiconductor/ferromagnet hybrid heterostructure that exhibits (i) a Ge barrier of diamond crystal structure, (ii) room-temperature ferromagnetic electrodes and (iii) very smooth interfaces. Both bottom- and top-Fe-Ge electrodes exhibit tiny in-plane magnetic anisotropies dominated by a magnetocrystalline contribution of six-fold symmetry originating from the hexagonal symmetry of the B82 (Ni2In) β-Fe-Ge phase. A key result is the absence of any magnetic coupling between these soft-magnetic electrodes for Ge barrier thickness as low as ~2.5 nm, which allows us to easily tune the parallel and antiparallel magnetic alignments by applying suitably small magnetic fields. This confirms the beneficial use of H-surfactant in order to drastically reduce the roughness of the Ge barrier, as revealed by our scanning tunneling microscopy and transmission electron microscopy measurements. This new all-epitaxial ferromagnet/semiconductor hybrid system appears, therefore, to be a promising candidate for the realization of magnetic tunnel junctions with a single crystal semiconductor barrier that are fully compatible with Si-based technology.